ALABAMA 135 



near the latitude of Tuscaloosa, a few miles north from the similar ter- 

 mination of the Cahaba field in Bibb county. The section in Jefferson 

 and Tuscaloosa is very long, showing somewhat more than 3,000 feet of 

 Coal Measures, fully 2,800 feet being above the Bonair sandstone. The 

 Etna sandstone, at about 40 feet above the Lower Carboniferous, is light 

 colored, massive, coarse, but without pebbles, and from 40 to 75 feet thick, 

 with the thin Etna coal bed immediately below it. and the Dade, or per- 

 haps a lower bench of the Etna, at from 3 to 10 feet lower. The Bonair, 

 30 to 50 feet thick, is somewhat pebbly, is about 50 feet above the Etna, 

 and rests on the Cashie coal bed. The Jackson and Sewanee horizons 

 are represented by coals at 5 and 41 feet above the Bonair. 



The detrital deposits above the Sewanee horizon show extreme varia- 

 bility, intervals being given as 50 to 300 feet, 25 to 125 feet, 60 to 225 feet 

 in the generalized section. Fossiliferous limestones, associated with sand- 

 stones also containing marine fossils, are at about 1,000, 1,300, 1,950, and 

 3,000 feet above the base of the formation, but these limestones are local 

 in distribution. Two persistent conglomerates, both thin, are shown, 

 one at about 1,500 feet above the base and the other toward the top of 

 the series. Several non-persistent conglomerates appear in the upper 

 600 feet of the section, but they are all thin and mere lentils. One may 

 recognize the third conglomerate of Blount mountain, and in the coarser 

 beds at the top of the section there appears to be the representative of 

 the conglomerates of the Coosa and Cahaba fields. Mr McCalley reports 

 50 coal beds above the Bonair, but for the most part they are very thin, 

 though several of them become economically important under large 

 areas. It is difficult, in the absence of detailed sections, to make proper 

 comparisons with the Coosa and Cahaba fields, but the thickness of the 

 coal beds in the Coosa field and the diminished number there seems to 

 suggest that the many beds reported by McCalley in the Warrior may 

 represent separated benches of thicker beds at the east. 



Variegated shales make their appearance at about 1,000 feet above 

 the base, and thence upward are of frequent occurrence. In Walker 

 county, west from Jefferson, a red sandstone, 25 feet thick, is shown at 

 a little way below the Third conglomerate. The rocks generally are 

 soft, and the sandstones tend to be shaly ; but the section in this county, 

 as well as in Fayette and Lamar westward to the- Mississippi border, 

 does not reach downward to the Bonair. 



Northward from this tier of counties the section becomes shorter, so 

 that in Cullman there remain only about 1,000 feet above the Bonair. 

 Here, as in Jefferson, no determination can be made of relations above 

 the Sewanee coal bed, which underlies about 500 feet of shales and 

 sandstones. Both Bonair and Etna are here, massive and more or less 



